Frequently Asked Questions

Below you can find Frequently Asked Questions (FAQ) about SERATEC® Products. If your cannot find the answer on a particular question in the list, please send us an e-mail. We will answer your question and upload it as FAQ on the website.

Specimens can be stored in refrigerators at 2 to 8° C for up to two (2) days (48 hours) or frozen at 0° C, before testing. However, it is strongly recommend testing the sample as soon as possible after collection.

Yes. The most common problem is the pseudoephedrine in many over-the-counter sinus and cold medications, which can cause a positive result for methamphetamine. A GC/MS confirmation as well as a MRO review is necessary to determine the source of the positive result. Some forms of the drugs we test for may be available legally under prescription as well.

No. The tests are drug and drug metabolite specific. Because these commonly ingested substances are chemically and structurally different after metabolized by the body from the drugs being tested for, they will under most circumstances not interfere with or compromise test results.

No difficult manipulation of sample material
The sample is transferred into the extraction buffer in the collection tube and extracted/dissolved by shaking. After that three drops of the liquid are added directly to the test.

Rapid generation of the test result
Results should be read within a ten minute period after addition of the sample.

High sensitivity
The lower detection limit is at least 40 ng/ml hemoglobin. This corresponds to human blood that has been diluted to 10-6 - 10–7 (average hemoglobin content of blood: 120-180 mg/ml).

High specificity for human hemoglobin
Due to the specificity of the antibodies, positive test results allow the direct conclusion that the sample most probably contains blood of human origin. A cross reactivity is observed for blood of primates and ferret blood.

The test contains two monoclonal anti-hemoglobin antibodies as active compounds. One of the antibodies has been immobilized as line in the test result region (T) of the membrane. The other antibody is gold-labeled. It is placed downstream of the membrane on a glass fibre pad and becomes mobilized by the addition of the liquid. If hemoglobin is present in the sample it will bind to the gold-labeled antibody forming a complex. Through the capillary effect of the membrane, the liquid moves across the membrane towards the test result region. Here the immobilized antibody that recognizes another epitope of hemoglobin will bind the hemoglobin complexed with the gold labelled antibody (formation of a sandwich complex). This can be seen by the appearance of the red test result line.
The control line is composed of a different antibody pair (rabbit antibodies/goat anti-rabbit antibodies) one of which is immobilized at the control region. The other one is gold-labelled and mobile. As these antibodies interact directly with each other, the control line is formed independent of the presence of hemoglobin. The appearance of the control line serves as an internal control for the correct performance of the test.

A high dose hook effect is observed, if too much free hemoglobin that is not bound to the gold-labeled antibody reaches the test result region. In this case the antibody immobilized at the test result region becomes saturated with free hemoglobin. This prevents the binding of the hemoglobin complexed with the gold-labeled antibody, thus interfering with the formation of the test result line. The test result appears negative in spite of the presence of hemoglobin in the sample.
The high dose hook effect can be avoided using the color of the sample as a guide. The visual detectable color caused by hemoglobin vanishes between a 10-3 and 10-4 dilution. At this concentration range there is no danger of a high dose hook effect. In contrast samples that are clearly colored due to hemoglobin are likely to cause false negative results because of the high dose hook effect. Good results are obtained when the extract has a "straw" color.
If you are concerned that a negative result is from High Dose Hook Effect, then a simple remedy is to dilute the extract and re-run the sample.

The SERATEC HemDirect immunoassays enables the user to identify traces of human blood in forensic sample material. In a specific antigen/antibody reaction, the presence of human hemoglobin can be determined within minutes. The test result is interpreted visually by the appearance of a red test result line in hemoglobin positive samples. The assay is rapid and easy to perform and requires no difficult manipulation of the sample material. If necessary, it can be performed directly at the crime scene.

Studies show that the SERATEC® LH MAX reliably detects the LH maximum with over 99% agreement. If you do not get pregnant although you had intercourse during the “fertile days” it could have some normal reasons and you should not worry about it. If you do not become pregnant after several months, you may want to consult your physician.

To determine the start of the test correctly you must know the length of your menstrual cycle. The first day the bleeding starts is counted as the first day of the cycle. The cycle lasts until the last day before the next bleeding of the following menstrual cycle occurs. Calculate the length of your cycles for the previous months. If there are slight variations (up to 4 days) take the mean. From the table on the first side of the instruction leaflet you can now see on what day of the cycle the test should begin.
Example: The normal length of your cycle is 28 days. The recommended starting day of the test series is the 11th day of your cycle (see table). Your last period started on June 5th.. Take a calendar and count 11 days starting from June 5th. You will see that the test series should be started on June 16th.

No. The control line (C) shows the same intensity of color for each test, so that each test can be interpreted independently. Each daily reading tells you whether or not you are about to ovulate. If the test result line (T) shows a similar or darker color than the control line (C) you have detected your LH surge. Ovulation should occur within 24-36 hours after the first positive result.

No, you can stop testing when you detect your LH surge and save the remaining tests for the next month, if necessary. However, if you are a first-time user, or if you are not sure whether you detected your LH surge, you may want to follow the rise and the fall of the LH level in your urine as depicted in the user instruction. This would reassure you in the prediction of the ovulation.

There are several explanations if you cannot detect an LH surge. One possibility is that you may not have ovulated in the particular month. This may occur occasionally, and it is normal. Another possibility is that you missed your LH surge and that it either occurred before or after the test series. This might be due to an irregular cycle or you may have miscalculated your menstrual cycle. You might want to continue testing with another test kit or start testing earlier in the next month. Also make sure that the urine sample was reliably collected. Different times of the day and irregular liquid uptake may interfere with the result of the test. If you continue to get readings that do not correspond to the expected results, please consult your physician.

All SERATEC® pregnancy tests, exept the early tests may be performed anytime. Its high sensitivity allows for diagnostics without the need of first morning urine.
For the SERATEC® early pregnancy tests morning urine should be used!

The intensity of the colour depends on the concentration of HCG in urine samples. According to how advanced pregnancy is, as well as on the individual rate of production and attenuation, the membrane may turn from slightly pink up to darkly red. Even the lightest observable coloured line in the region of indication shows the presence of HCG and means therefore a positive result.

The accomplishment of the Test is quite simple. Therefore its result is normally faultless. While the whole membrane turns slightly red during reaction, the colour fades away shortly afterwards.

The result of the Test remains valid, even if the membrane is kept in the urine sample for more than 15 seconds or is exposed to a urine stream for over 8 seconds. Moreover, the result does not change even if it is read after a period longer than 3 minutes after its start. If the membrane is not impregnated sufficiently with urine, the Test may not be run correctly. Under these circumstances liquid residues may appear as lines („ghost lines“’), leading to an apparently positive outcome. This may be prevented for by exposing the Test to urine again immediately.
The outcome may be apparently negative if it is read within a period shorter than the indicated.

Exposure of the entire surface of the Test to the urine sample does not lead to failure.

HCG concentrations lower than the minimum specified (10-25 mlU/mL) may show an apparently positive outcome past 15 to 30 minutes, especially when the Test is performed long before the end of the menstruation period.

According to the scientific and technological state of the art it is most improbable to observe a wrong positive outcome. SERATEC® pregnancy tests are manufactured in accordance to the European Health Standards and submit to a severe quality control, to ensure that even a slight indication corresponds to a concentration of HCG higher than the normal. The most common reasons for a wrong indication are listed below:

Consumption of medicaments containing HCG.

Degeneration of the Plazenta following uncontrolled appearance of Corionzotes. Formation of Corionzotes results from the merge of two sperms with a Y-chromosome. Upon diagnose abnormally high HCG concentrations are observed as well as the fading of the ultrasound-image of the ovaries.

Chorio-carcinoma.

Hindered transport of the ovum through the fallopian tube leading to a nestling of the embryo.

Pregnancy interruption caused or followed by premature abortion. About one third up to half of all pregnant woman suffer a premature abortion within the first 12 weeks. So-called hindered pregnancies show a delayed evolution compared to normal. HCG secretion occurs at a lower rate leading to a smaller relative concentration. Furthermore HCG my be detected even after an abortion, as the time required for it to vanish varies individually.

Missed abortion.

Normal pregnancy stages menaced by abortion due to immunological failure.

Running of the pregnancy test at too low HCG concentrations, in case of a premature measurement, or if ovulation occurs clearly towards the end of the period, or if a strong attenuation is caused by increased passing of water.

In the event of a mutated HCG detection. Only very few women show alterations in the binding positions of the HCG-Molecule, avoiding interaction with the specific antibody. In such cases a different test based on detection with a different antibody may of course have different outcome. This phenomenon is known in modern Medical Diagnostics as a consequence of the unique individual genetic and biological skills. Therefore no single immunological test is exempted from failure under these quite rare circumstances.

All sorts of membrane tests are highly sensible to humidity. The shelf life of the SERATEC® pregnancy tests may last up to several years as long as it remains sealed in a pouch containing a drying-gel envelope inside (standard packing conditions). Tests exposed to regular air humidity without being used may loose sensitivity after some hours and show only very thin lines in both the indication and the control regions, or no lines at all. Damage of the pouch may lead to loss of sensitivity as well. A severe quality control (manually performed) mostly prevents for the distribution of damaged Tests.

The tests should be stored at temperatures between 2°C and 30°C. Temperatures below 0°C or above 30°C lead to a decrease of the shelf life. The regular period of 2 years cannot be guaranteed unless these conditions are observed. Beyond 60°C physical processes occur, which lead to the irreversible destruction of the Tests.
Tests should be run at room temperature (between 18°C and 25°C) to avoid decreased sensitivity and flow rates of urine through the membrane.

The 4 ng internal standard allows the analyst to estimate the concentration of PSA in the sample and determine the likely method of analysis to obtain a DNA profile. Concentrations greater than 4 ng/mL may yield a nuclear DNA profile from nucleated cells in the seminal fluid whereas PSA values less than 4 ng/mL generally require Y-STR DNA analysis.

PSA is now known to be found at very low levels in many different fluids and tissues including breast tissue and tumors, periurethral glands, breast milk, amniotic fluid and female urine. However, PSA levels in semen average 800,000 ng/mL. So by proper dilution of the sample, it is possible to determine that a positive result is unequivocally due to the presence of human seminal fluid.

The SERATEC® PSA SEMIQUANT test is a chromatographic immunoassay (CIA) for the rapid semi-quantitative determination of PSA in body fluids. It contains two monoclonal murine anti-PSA antibodies as active compounds. One of these antibodies is immobilized at the test region on the membrane. The upstream control
region and the region of the internal standard (between control and test region) contain immobilized polyclonal goat anti-mouse antibodies. The amount of antibody at the internal standard is adjusted to a level at which the line produced equates to a concentration of 4 ng PSA/mL. A glass fiber pad downstream of the membrane is used for sample loading and transmission to a second fiber pad with the dried and gold labeled second monoclonal murine anti-PSA antibody. PSA at the sample will bind to the remobilized gold-labeled antibody and form a PSA-gold-labeled-anti- PSA-antibody-complex. Through the capillary effect of the membrane, the reaction mixture including the complex is carried upwards with the fluid. In any case the colored gold labeled anti-PSA-antibody will bind to the anti-mouseantibody at the control region and the region of the internal standard thus developing two red lines (one at the control region ant one at the region of the internal standard). These two lines are independent of the existence of PSA in the sample and indicate only the correct execution of the test.
If the sample contains PSA, the PSA-gold-labeled anti-PSA-antibody complex will bind to the immobilized monoclonal antibody of the test result region that recognizes another epitope on the PSA molecule (sandwich complex). The binding is indicated by the formation of an additional line. Thus a PSA positive sample will show three colored lines in the result window. The line in the middle (internal standard) correlates with an amount of 4 ng/ml PSA. In some cases it might be helpful to estimate the amount of PSA in the sample by comparison of the test result line with the internal standard line.

PSA (Prostate-specific antigen) is a glycoprotein produced in the prostate and secreted into the seminal fluid. PSA is one of the major proteins in seminal fluid with concentrations of 0.2 to 3.0 mg/ml. Its main function is to liquefy the seminal fluid. This high amount and the fact that PSA is found only at very low concentrations in female vaginal fluid (0.4-0.9 ng/mL and 0.0-1.25 ng/mL, respectively) make PSA an interesting marker in forensic science for the detection of even small amounts of seminal fluid.

Contact a Representative to Enquire or Order

Site Links

Company

Diagnostics

Use of this site constitutes acceptance of the SERATEC® terms & conditions and privacy policy. Contents of the SERATEC® site are for informational purposes only and not intended to be a substitute for professional medical advice, diagnosis, or treatment.